Few things seem to capture the minds of newspaper and magazine editors these days, particularly on the web, more than studies they can distort to look like proofs against Einstein. A surefire way to make it to the top is to spew out a news story about a theory that is best described by such catchy phrases as “might prove the foundations of modern physics wrong” and “contradicts Einstein’s theory”. A little music and Star Trek-inspired warp drive visuals in the background will certainly help take it the extra mile. But, really, how accurate is it?
While it might seem like wishful thinking that some theory may come along tomorrow or the day after that answers all our questions, the reality is that we slowly nudge in the right direction, sometimes wander off track, return, trip and find our way again. That is generally how science is done. And at no point, you will notice, has it ever been about proving Einstein wrong.
“The critical geometry of a thermal big bang” is the title of a paper that was published in PhysRev D recently (preprint on ArXiv) by physicists Niayesh Afshordi and Joao Magueijo. Admittedly, this title is not half as catchy as “We disproved Einstein, here’s some cake”, but if they did title it that way, it would be unlikely that anybody in the scientific community would ever read it.
As a researcher I found the abstract interesting and decided to read the paper. A couple of weeks later, to my surprise, I found The Guardian of all media outlets touting it in their science section with a rather catchy title: “Was Einstein wrong? Physicists challenge speed of light theory”. They even have what they call a video explainer that carries the two catchy phrases stated in the lede.
This sort of thing gets on my nerves but that is not even the least important effect it has: science is undermined, its nuances are oversimplified and flattened and tossed aside; the real work physicists have done is, quite simply, misrepresented. To their credit, the authors themselves have never claimed to be spearheading a global effort to prove Einstein wrong. And even if he is proved wrong, so what? It would be just another day in physics.
So where did this come from in the first place? Before (or instead of) jumping into the paper itself, look at the source most non-scientific mainstream media turn to for science news: press releases. Imperial College, where Prof Magueijo works, published one titled “Theory that challenges Einstein’s physics could soon be put to the test”.
The key part of this title is not about challenging Einstein but rather about the theory’s predictions being testable. In fact the theory in question is actually over a quarter of a century old. There just was no predictable quantities until now that could be tested for.
The problem being addressed by the theory has to do with the Big Bang: if Einstein’s constancy of speed has always been true (temporally, not spatially) then there is simply no way light could have reached all parts of the universe since the big bang, and yet all parts share the same physical parameters like temperature. In other words, there is a “high degree of uniformity of the cosmic microwave background“ which puts before us a problem called the homogeneity problem or the horizon problem. (There is an interesting explainer by one C.D. McCoy called “What is the horizon problem?” that explains this in much greater detail.)
One solution that has been proposed for this, and is often the most accepted one, is “Inflation”. It requires a billionth of a billionth of a billionth of a ten-thousandth of a second’s worth of exponential expansion to have occurred during the earliest stages of the universe. The crux of this theory, and why it has garnered many supporters, lies in the fact that it works without disturbing any existing fundamental ideology.
The other solution is really a class of theories called “variable speed of light theories” that require that the velocity of light be much grater than c in the early days of the universe (this is specifically 60 times c in Prof Magueijo’s proposition) and this would, in turn, explain how the far edges of the universe could have “contacted” each other in a bid to regulate their physical parameters. The VSL class of theories itself were proposed ten years before Prof Magueijo by Jean-Pierre Petit.
The authors state, at least twice, that while their predicted spectral index appears to be more than just believable, improved observational accuracy can easily prove or disprove their theory.
The paper in question is lengthy and thorough, and from even the briefest of glances one can say that anything about, and any manner in, which it addresses Einstein has nothing to do with making him abdicate his position as one of the greatest minds of physics. It is time to set things straight.
They use specific calculations founded on the density fluctuations in the early, expanding universe to predict the spectral index, a specific relation between the power of a radiation through a given area and either its frequency or its amplitude (and the only reason I happen to know this is because of my time spent at the Astrophysics Institute).
Whereas most other models are built around observed values of this spectral index, in turn built on the constancy of the speed of light, the Magueijo-Afshordi model arrives at a meaningful, fixed value of the spectral index which, being “within observational scales”, can actually, realistically be expected to be observed. Last year, the Planck experiment did, in fact, observe these ranges for the spectral index.
The authors really say nothing about Einstein, and no physicist does for that matter. They state, at least twice if I recall correctly, that while their predicted spectral index appears more than just believable, improved observational accuracy can easily prove or disprove their theory; to wit, this theory works like how any other theory does and its elegance lies in their treatment of the geometry of space-time rather than a brash fight they would appear to have picked up with Einstein if one goes by regular media.
So, firstly, regular newspapers should probably not be anybody’s source of scientific news (and I have said this on many an occasion before), and, now that I think of it, there is one particular sentence I liked in the paper that I think can be broadened to speak for all of science and will be a sound conclusion to this essay. At one point they say, “The fact that [the prediction for the spectral index] lies spot in the middle of the Planck results should not beguile us into a false sense of security.” And celebration, if I may add.
Do take note, The Guardian, and spend your journalistic resources on something other than goofy videos that make real physics sound like Einstein-trumping conspiracy theories. And all media outlets should, at least, be more faithful towards physics and less insistent on oversimplifying it to the point where the original research itself gets misshaped. ❖